The human bed bug Cimex lectularius is a hematophagous insect that requires a blood meal for growth and development. Over the past decade, bed bug infestations have grown virtually exponentially in both North America and Europe (Hwang et al., (2005) Emerging Infectious Diseases 11(4), 533-538). Although the exact conditions prompting the recent resurgences is uncertain, the rise in bed bug infestations nationwide has been linked to increased international travel, changes in pest management practices, and increased insecticide resistance (Romero et al., Journal of Medical Entomology 44(2), 175-178 (2007); Potter, Pest Control Technology 33, (2005)).
Current bed bug control measures rely heavily on the use of pyrethroid insecticides. However, increased insecticide resistance threatens bed bug control efforts throughout the world (Moore and Miller, (2006). Journal of Economic Entomology 99, 2080-2086; Romero et al., 2007; Yoon et al., Journal of Medical Entomology 4, 1092-1101 (2008); Seong et al., Journal of Medical Entomology 47, 592-599 (2010)). In addition to pyrethroids, bed bugs are known to be resistant to DDT in Israel (Levinson, Riv. Parassit., 14, 233 (1953)), French Guiana (Floch, Rapp. Institut Pasteur de la Guyane, p. 152 (1955)), Greece, Italy, China, and Iran (Busvine, Bull. World Health Organization 19, 1041-1052 (1958)). Bed bugs demonstrate significant agility and evolutionary resistance to various chemical insecticides and pesticides. Pesticide resistance is a major reason for the recent bed bug resurgence (Potter, 2005). In addition, pesticide resistance results in increased application rates and frequencies that unnecessarily expose humans and animals to these toxins. Due to the impact of insecticide resistance, there is potential for developing alternative methods of bed bug control.
One such alternative is the formulation of entomopathogens as biopesticides. With their documented low mammalian toxicity (Zimmerman, Biocontrol Sci. Technol., 17: 553-596 (2007) and Zimmerman, Biocontrol Sci. Technol., 17: 879-920 (2007)) entomopathogenic fungi have great potential for development as components of a comprehensive integrated pest management approach that includes pest monitoring, sanitation and resident education.
The entomopathogenic fungus Beauveria bassiana is capable of infecting a broad range of insect hosts and has been used in horticulture, agriculture, mosquito control, and soil insect control. In the past, entomopathogenic fungi have been used to control agriculture and forest pests including the gypsy moth Lymantria dispar (Elkinton et al., Environmental Entomology 20, 1601-1605 (1991); Hajek et al., Journal of Environmental Entomology 25, 1235-1247 (1996)), and various species of aphids (Hall, Microbial control of pests and plant diseases 1970-1980. Academic Press, London, pp 483-498 (1981); Milner, Entomophaga 42, 227-23 (1997); Yeo et al., Pest Management Science 59, 156-165 (2003)), and locusts (Lomer et al, Annual Review of Entomology 46, 667-702 (2001)).
In addition, recent research has illustrated the effectiveness of entomopathogenic fungi on blood feeding insects and disease vectors including Triatoma infestans (Pedrini et al., Neglected Tropical Diseases 3(2), 1-11 (2009)) and several species of mosquito (Blanford et al., Science 308, 1638-1641 (2005); Blanford et al., PLoS One. 6(8): e23591 (2011)). Once germinated, the conidia of entomopathogenic fungi penetrate directly through the cuticle of the insect. Once inside, the fungus produces metabolites that kill the insect as a result of nutrient sequestration and internal mechanical damage (Gillespie and Clayton, Pesticide Science 27, 203-215 (1989)).
Importantly, it has been shown that insecticide resistance confers no cross-resistance to entomopathogenic fungi in mosquitoes (Farenhorst et al., PNAs 106(41), 17443-17447 (2008); Blanford et al., 2011). In addition, research on mosquitoes suggests that fungal infection leads to insect death beginning at day three (Scholte et al., Proceedings of the Section Experimental and Applied Entomology of the Netherlands Entomological Society (NEV) 14, 25-29 (2003); Blanford et al., 2005). Since this kill time is slow compared to pesticides, fungal infected insects may have the opportunity to reproduce, which could reduce selection pressure for insecticide resistance (Hancock et al., Proceedings of the Royal Society of London B 276, 71-80 (2009); Koella et al., Evolutionary Applications 2: 469-480 (2009)). Understanding bed bug susceptibility to biopesticides can have important implications in bed bug management practices.
There remains a significant need for improved bed bug management practices. Current infestations of bed bugs can result in significant costs, including for example, direct cost of treatments (insecticides and/or pesticides, fuming, cleaning, laundering, etc.), and indirect costs (e.g. lost profits). For example, an infestation of a hotel room with bed bugs requires the use of insecticides, heat or cold treatment, and/or fumigation. This generally requires vacating and treating the infested room and all surrounding rooms (including above and below) due to the risk of harborages in adjoining infrastructures. In addition, there are also significant psychological effects of having a bed bug infestation. As a result, there is significant need for less time consuming and more efficacious treatments, along with prophylactic measures for preventing bed bug infestations.
Accordingly, it is an objective of the claimed invention to develop compositions and methods for use in employing entomopathogenic fungi for controlling bed bug populations and/or preventing bed bug infestations.
A further object of the invention are compositions and methods for using entomopathogenic fungi to control and/or prevent bed bug populations of various feeding statuses, sexes, strains, exposure substrates, and at varying life history stages.
A further object of the invention is compositions and methods for using entomopathogenic fungi as a superior alternative mode of action for bed bug control and/or prophylaxis in comparison to pyrethroid, resulting in the reduction of pyrethroid resistance in bed bugs.
A still further object of the invention is to provide compositions and methods for bed bug population control and/or prophylaxis that are superior to standard chemical treatments, as a result of targeting all concealed harborages in established infestations through the horizontal transmission of entomopathogenic fungi. These and other aspects of the invention are set forth in further detail within the description of the invention.